splice: fix i_mutex locking in generic_splice_write()

Rearrange locking of i_mutex on destination so it's only held while
buffers are copied with the pipe_to_file() actor, and not while
waiting for more data on the pipe.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 23 insertions, 11 deletions

diff --git a/fs/splice.c b/fs/splice.c
index 349576b2c75a..a1f595b9db40 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -895,17 +895,29 @@ generic_file_splice_write(struct pipe_inode_info *pipe, struct file *out,
         };
         ssize_t ret;
 
-        WARN_ON(S_ISFIFO(inode->i_mode));
-        mutex_lock_nested(&inode->i_mutex, I_MUTEX_PARENT);
-        ret = file_remove_suid(out);
-        if (likely(!ret)) {
-                if (pipe->inode)
-                        mutex_lock_nested(&pipe->inode->i_mutex, I_MUTEX_CHILD);
-                ret = __splice_from_pipe(pipe, &sd, pipe_to_file);
-                if (pipe->inode)
-                        mutex_unlock(&pipe->inode->i_mutex);
-        }
-        mutex_unlock(&inode->i_mutex);
+        if (pipe->inode)
+                mutex_lock_nested(&pipe->inode->i_mutex, I_MUTEX_PARENT);
+
+        splice_from_pipe_begin(&sd);
+        do {
+                ret = splice_from_pipe_next(pipe, &sd);
+                if (ret <= 0)
+                        break;
+
+                mutex_lock_nested(&inode->i_mutex, I_MUTEX_CHILD);
+                ret = file_remove_suid(out);
+                if (!ret)
+                        ret = splice_from_pipe_feed(pipe, &sd, pipe_to_file);
+                mutex_unlock(&inode->i_mutex);
+        } while (ret > 0);
+        splice_from_pipe_end(pipe, &sd);
+
+        if (pipe->inode)
+                mutex_unlock(&pipe->inode->i_mutex);
+
+        if (sd.num_spliced)
+                ret = sd.num_spliced;
+
         if (ret > 0) {
                 unsigned long nr_pages;